Hydraulic power gripping apparatus



2 Sheets-Sheet 1 A A-A a "Hanan"! J- S. MONTGOMERY ETAL HYDRAULIC POWER GRIPPING APPARATUS Feb. 2, 1960 Filed Jan. 15, 1958 INVENTOR. 559 5. Monfg'amery BYcF: W/W/a/n C. Hu/fon ATTORNEY 762: 7 a

Feb. 2, 1960 5, MONTGOMERY ETAL 2,923,192

HYDRAULIC POWER GRIPPING APPARATUS Filed Jan. 15, 1958 2 Sheets-Sheet 2 2-way control valve for fluid in 25 pistons I5 adjustable pressure valve 87 for .9/

ea hydraulic fluid storage tank fizf. 3

cylinder reversible molar power valve cylinder 5 INVENTOR. Jesse 5. Mango/fiery BY d5 Wf/uem C. Huf/on ATTORNEY HYDRAULIC POWER GRIPPING APPARATUS Jesse S. Montgomery and William C. Hutton, flklahoma City, Okla, assignors to Fluid Power Corporation, Gklahoma City, Okla., a corporation of Oklahoma Application January 15, 1958, Serial No. 709,050

9 Claims. (CI. 81-53) This invention relates to improvements in power tongs for making and breaking of threaded joints, and more particularly, but not by way of limitation, to an automatic power tong apparatus for use in screwing or unscrewing sections of drill pipe, drill rods and the like used in the drilling of oil well bores.

It is well known that with the increase in depth of the drilling of oil wells that the drilling string must be jointed and unjointed many more times, consequently, a reduction in the labor and time necessary for performing the steps of making up or unthreading the threaded joints is of primary importance.

The present invention is concerned with a power tong apparatus for the making up and unthreading of sections of oil well drill pipe in a manner to speed up the initial make up connection with a subsequent increase in the torque application for a more positive make up, and in the reverse operation for unthreading by utilization of the greater torque for unthreading the tight joint, or even frozen joint, which after being loosened is increased to faster rotation for an over-all efficiency in the make up and unthreading operation. The invention provides a plurality of circumfereutially disposed gripping members for engaging the pipe to be operated on which are disposed in a gear wheel adapted for variable rotations with an initial increase in rotation to initially speed up the make up connection, and then subsequently rotated at a slower speed for application of an increased torque; and in the reverse operation of unthreading, the gear wheel is initially rotated slower atgreater torque, and as the torque is lessened, the rotation is speeded up accordingly.

It is an important object of the present invention to provide a novel power tong assembly which is adaptable for use with the drilling rig and capable of operation therewith at all times.

And still another object of the invention is to provide a power tong assembly in which the steps of fast, free and easy threading, and of hard tightening can be performed in one continuous operation without any interruption in the make up of the joint.

And still another object of this invention is to provide a power tong apparatus in which the steps of initially breaking or unscrewing ajoint at an increased torque with subsequent free and easy unscrewing thereof can be performed in one continuous operation.

And still another object of this invention is to provide a power tong apparatus for making up drill pipe connections in oil field drilling strings which includes the steps of rotating the pipe with a number of revolutions at a low torque followed by a partial turn or revolution at a high torque, thereby providing a fast make up initially at low torque with a subsequent decrease in revolutions at the high torque, thus providing a considerable differential in torque requirements and effecting an economy in the power requirements for application of the tong apparatus.

And still another object of this invention is to provide 2,923,192 en d E b- 1969 section to be operated on,

An additional object of this invention is to provide hydraulically actuated power tongs wherein the torque may be controlled through the use of an adjustable valve for controlling the hydraulic pressure to be applied.

And still another object of this invention is to provide a power tong apparatus which is designed for simplicity in operation, durability, as well as economy of power requirements and efficiency in over-all operation.

Other objects and advantages of the invention will be evident from the following detailed description, readin conjunction with the accompanying drawings, which illustrate our invention.

In the drawings:

Figure 1 is a sectional plan view showing the full lay out of the'gear wheel and the actuating pistons and power valve.

Figure 2 is a vertical sectional view partly in elevation and showing the gripping pistons against the gear Wheel and the connection of the hydraulic motor thereto.

Figure 3 is a schematic layout of the power connections.

Figure 4 is a perspective view showing the exterior of the unit.

Referring to the drawings in detail, the power unit 1 comprises a suitable base 2 (Figs. 1, 2 and 4) adapted to be supported on the rotary table or on a swingable tripod of an oil well derrick so that the central bore 3 thereof is brought into alignment with the bore of the oil well or the like for insertion of the pipe to be operated on therein. There are numerous ways that the unit and base 2 may cooperate with the rotary table for receiving the pipe and if it is to be fixed to the rotary table, any suitable means for securing thereto, such as bolts or the like, may be utilized. The power tong unit 1 in addition to the base comprises an upstanding centrally disposed circular flange portion 4 which is separate from the base 2 as at 6, and secured thereto in any suitable manner (not shown). The base 2 is provided with a hollow interior 7 and is adapted to receive a circular gear wheel 8 having a central hub 9 with upstanding portions 10 and outwardly depending legs 11. A vertical flange 12 is provided on each end thereof. The gear wheel 8 is preferably provided with three legs 11 preferably spaced 120 degrees apart, but not limited thereto. A peripheral rim 8a of the wheel 8 is provided with a plurality of gear teeth 13 extending completely around the circumference thereof for a purpose as will be hereinafter set forth.

As shown in Fig. 1, each of the gear wheel legs ll'is provided with a recessed portion 14 for receiving a slidable piston member 15 having serrations or teeth 16 on the inwardly disposed end thereof. The piston 15 is provided with an axial recess 17 in which is disposed a helical spring is anchored around a threaded stud 19 with one end of the spring anchored to the stud head 20 and the other end against inwardly directed flanges 21 of the piston 15. An aperture 22 is provided between the flanges 21 and through which the threaded end 23 of the stud anchors into the flange portion 12 of the wheel 8. The aperture 22 is in communication with a port 24 pro vided in the leg body 11 and extending into the upstanding centrally disposed portion (Fig. 2) of the wheel 8 into communication with a larger port 25 provided in the separable flange hub of the power unit 1. The port 25 communicates with a central valve and pump for re-v ceiving hydraulic fluid such as oil or the like in a manner and for a purpose as will be hereinafter set forth. The flange 4 is provided with a suitable recess 26 for receiving suitable packings 28 to prevent leakage of the oil during the flow through the conduit 24. Furthermore, the base 2 is provided with suitable upper and lower roller bearings 29 and 30 adjacent the hub 9 in order to properly support the wheel 8 during its rotation within the base 2.

At one side of the base 2 and adjacent the upper flange 4 there is provided a suitable reversible hydraulic motor 32 having a shaft 33 extending through an apertured portion 34 of the base 2. The shaft 33 has secured thereto a suitable gear 35 (Fig. 2) having teeth 36 engaging with the teeth 13 of the large gear wheel in a manner as will be hereinafter set forth.

At opposite ends on one side of the base 2 there is provided apertured portions 38 and 39 through which is disposed piston cylinders 40 and 41, respectively. The

cylinders are pivotally secured to the base in any suitable manner, such as trunnion type bearings or pins 4 2 and 43, permitting pivotal movement of a complete cylinder and its adjacent parts as will now be explained. Extending from each of the cylinders is a rack guide 44 slidably supporting a rack member 45 through the guide pin 46 in any suitable manner, such as slots or the like (not shown). A suitable type of circular piston 48 is provided in the cylinder 40 and in like manner, a piston 48a is provided in the cylinder 41. The piston 48 is provided with an axially disposed piston rod 49 extending outwardly from the cylinder 41 through a packed aperture 50 to a position adjacent the rack guide 4-4 and into threaded connection with the flanged end 51 of the rack 45 so that upon sliding movement of the piston, there will be simultaneous reciprocation of the rack member 45. The rack member 45 is provided with suitable teeth 52 adapted to be engaged with the peripheral teeth 13 of the main gear wheel 8. It will be apparent that each of the pistons 48 and 48a is provided with a rack member 45 and 45a at opposite sides of the base member 2. The opposite ends of each of the cylinders 40 and 41 are provided with apertured flange members 53 and '54, respectively. The upper flange member 53 is secured by a pivot pin 55 to an outwardly extending leg 56 of a hydraulic actuator or power motor 57a. The flange 54 for the cylinder 41 is secured by a pivot pin 58 to a leg 59 threadedly secured at 69 to a piston rod 61 extending outwardly from the power valve cylinder 57 of the power motor 57a and integral with the multiple flanged piston 62 disposed within the cylinder. The valve cylinder 57 is provided with a plurality of port openings 63, 64, 65, 66 and 67 for a purpose as will be hereinafter set forth. A suitable bearing 68 is provided in the cylinder 57 for journaling the shaft 61 and thus maintain alignment during the reciprocation thereof.

A suitable reversing valve 70 is shown disposed substantially adjacent the power valve cylinder 57 and in communication therewith. However, it will be apparent that this reversing valve may be disposed any place in proximity thereof or remotely from the power valve 57, as long as it communicates therewith. The valve is provided with four ports 71, 72, 73 and 74 cooperating with conduits, for such communication. The port 71 is in communication with an opening 75 provided at one end of the cylinder 40 through a conduit 76. The conduit 76 in turn communicates through a conduit 77 connecting with an opening 73 in the cylinder 41 and disposed at an opposite end to that of the opening 75 in the cylinder 40. In like manner, the port 73 communicates with an opening 79 provided at the opposite end of the cylinder 41, and also connects with a conduit 89 connecting with a port 81 at one end of the cylinder 48. The port 74 communicates with port 67 of the power valve 57 through a conduit 82, and the port 72 communicates with the port 66 of the power valve 57 through a conduit 83.

The port 63 of the power valve 57 is adapted to communicate with any suitablefour way control valve 85 (Fig. 3) through a conduit 84. In like manner, the port 65 communicates with the valve 85 through a conduit 86. The port 64 of the power valve 57 communicates with a storage tank 89 of hydraulic fluid shown schematically in Fig. 3 through a conduit 87. The control valve- 85 also communicates with the tank 89 through a conduit 90.

Referring to the schematic drawing in 'Fig. 3, it will be seen that the valve 85 communicates through a conduit 92 with a suitable pump 91 for creating a suction on the tank 89 and pumping suitable hydraulic fluid through the valve 85, and alternately into the conduits 84 and 86, depending upon the position of the control valve 85. The variouspositions of the valve are manipulated by a suitable lever (not shown). In one position of the valve 85, the hydraulic fluid is directed through the conduit 84 into power valve 57 and inlet 63 to cause movement of the valve piston 62 in one direction, whereas manipulation of the valve 85 in another position will direct flow of fluid through the conduit 86 into the inlet 65 of the power valve 57 to cause movement of the piston 62 in an opposite direction for a purpose as will be hereinafter set forth. The valve 85 can be any suitable type valve having a neutral position, as desired.

As shown in Fig. 3, each of the gripping pistons 15 communicate with a manually operated two way valve 93 of any suitable type through the conduit 94 and inlet port 25, and in turn conduit 94 communicates with a suitable pump 95. The pump in turn is connected through a suitable conduit 96 with the storage tank 89. In one position of the valve 93, the pump directs fluid therethrough into the inlet 25 and passageways 24 to be exerted against the end 97 of a piston 15, thereby moving the piston 15 and the end teeth 16 thereof into gripping engagement with a pipe 98 disposed in the hub 9 of the main wheel or gear 8. It will be apparent that each of the three legs 11 of the wheel 8 is provided with a gripping piston 15, thereby providing a circumferentially spaced gripping action against the pipe 98. These hydraulically actuated gripping pistons for the purpose of holding the pipe 98 in position in the aperture 3 of the gear wheel and causing it to rotate with the wheel accordingly.

Operation In operation, if it is desired to connect a section of drill pipe or the like such as 98 with an uppermost section of pipe disposed in the well bore (not shown), the pipe 98 is manipulated into the aperture 3 by conventional hoisting and manipulating equipment for an oil well, and once the pipe is in position, the valve 93 is operated to provide discharge of power fluid from storage tank 89 to pipe 25 and hence to the port 24- to cause the gripping pistons 15 to engage with the outer periphery thereof and maintain the pipe in alignment and in temporary fixed relation with the power wheel 8. In this position, if it is desired to make up or thread the pipe so disposed in th gear wheel with a lower section of pipe below the surface in the well bore, the reversible hydraulic motor 32 is actuated by any suitable means, such as a suitable source of hydraulic pressure fluid, to cause a fast rotation of the motor shaft 33 and gear 35 so that the teeth 36 engaging theiteeth 13 of the gear wheel 8 will cause a fast run up or make up of the section of pipe through faster r.p.rn. of the wheel. When the make up connection approaches a limiting torque or stall of the hydraulic motor 32, the four way valve 85 is opened to direct hydraulic through the inlet port 63 into contact with one end 99 of the piston 62, thereby moving the piston axially in one direction according to the position of the arrow (Fig. 1),

It will be apparent that the hydraulic fluid also acts against the end face 100 of the valve cylinder 57, thereby simultaneously moving the piston 62, piston rod 61 and connecting lever 59 in one direction. In this operation, the lever 56 for the cylinder 40 moves in an opposite direction. It will thus be apparent that the piston cylinders 40 and 41 are moved in opposite directions about their respective piston pins 42 and 43. This pivotal action is provided for by the pivotal connection at.55 and 58, respectively. The pivotal movement of the piston cylinders 40 and 41 moves each of the racks 45 and teeth 52 thereof into engagement with the teeth 13 on the gear wheel 8. It will be apparent that the piston 62 in the power motor 57a provides a metering of the hydraulic fluid in that as soon as the piston is moved by the application of hydraulic fluid from inlet 63 to cause a pivoting action of the cylinders 40 and 41, there is an initial engagement of the racks 45 and 45a with the gear wheel 8. This engagement is substantially positive before the piston 62 is moved sufliciently to uncover the port 67 for directing hydraulic fluid through the conduits 82, 7'6, 77 to cause sliding movement of the pistons 48 and 48a and rotation of the wheel 8 through the connected rack mechanisms. This initial engagement prevents any undue chattering of the rack teeth 52.

In this position of engagement, the valve piston 62 has moved so that hydraulic fluid is directed from the inlet port '63 through the outlet port 67 into communication with the conduit 82 providing communication with the inlet port 74 of the reversing valve 70. The port 74 communicates with the port 71 through any suitable conduit 181 of the valve, and the port 71 in turn communicates with a conduit 76 connecting with the port 75 at one end of the cylinder 40. The conduit 77 connects With the conduit 76 and extends into connection with the port 78 of the cylinder 41. In this manner, hydraulic fluid is directed against an end 102 of the piston 48 in the cylinder 41 and simultaneously against an opposite face 113 of the piston 48a in the other cylinder 40. This hydraulic force causes movement of the piston 48 in a left hand direction according to Fig. l for the cylinder 41, and a right hand movement of the other piston 48a in cylinder 40. Movements of the pistons '48 and 48a in opposite directions respectively provide simultaneous movements of the racks 45 and 45a in the same directions, respectively. In other words, the rack 45 moves in a left hand direction and the rack 45a moves in a right hand direction in accordance with Fig. l causing a clockwise rotation of the gear wheel 8 and a continued make up or threading of the pipe 98 with the lower section of pipe in the well bore (not shown).

The amount of hydraulic pressure exerted for making up the pipe connections is equal to the capacity of the pump directing the hydraulic fluid through four way valve 85, however, to assure a limitation on the amount, a suitable adjustable pressure valve 103 (Fig. 3) connects between the pump line and the tank line to assure limitation on the pump. It will be apparent that the valve 103 may be adjusted to provide a predetermined amount of hydraulic pressure desired for providing the necessary pressure and torque on the wheel 8 for making up the connection between the pipe sections. It will be apparent that in large size pipe, the make up connection will require more torque and an adjustment of the valve for higher pressures, while on smaller size pipe, the pressure may be lessened.

After the make up connection, it is sometimes found that in order to provide a positive and complete make up connection between the pipe sections, it is necessary to disengage the rack members 45 and 45a and take another bite on the pipe, or provide another engagement with the gear teeth 13 to continue the rotation of the Wheel 8 for the make up connection. In order to disengage the racks 45 and 45a and their respective teeth 52, the four way valve 85 is manipulated through the handle (not shown) to direct the flow through th e con-- duit 86 into the port 65, thereby moving the piston 62 in a direction toward the end face 100. This movement of the piston '62 causes a pivotal action for the cylinders 40 and 41 about their respective pivot pins 42 and43 in a direction to move the teeth 52 of the racks 45 and 45a away from the teeth 13 for a disengagement there from. In this position (not shown) of the piston 62,- the hydraulic pressure fluid is directed from the port 66 of the cylinder 57 through the conduit 83 into the port 72 of the reversing valve 70, which in turn is connected through the conduit 104 with the port 73 communicating with the conduit 69 directing the pressure fluid to the port 79 of the piston cylinder 41. In similar manner, pressure fluid is directed through the auxiliary conduit 84) to the port 81 of the piston cylinder 40. When it is desired to re-engage the rack members with the gear wheel, the reversing valve 85 is manipulated in a manner (not shown) to again direct the pressure fluid into the porting 71, conduits 76 and 77, respectively, as has been hereinbefore set forth for moving the racks 45 and 45a into engagement with the gear wheel 8, whereupon a subsequent rotation of the gear wheel 8 in a clockwise direction will continue the makeup connection.

When it is desired to unthread the pipe, the reversing valve 70 is manipulated in any suitable manner as is well known for any conventional four way valve'in order to change the interconnecting flow of the valve'which was originally from -ports 74, 71 and 73,121 to cause the flowato be directed from port 74 to 73 through conduits 105, 7'2, 71 through conduit 106, thereby causing the pressure fluid from conduit 82 to be directed the conduit 69 into port 79 thereby directing the pressure against the face 107 of the piston 48. The auxiliary conduit 80 directs the pressure in the port 81 and against the face 168 of the piston 48a, thereby moving the pistons in opposite directions to cause a counter-clockwise rotation of the wheel 8 and an unthreading thereof. It will be apparent that as soon as the torque in' the unthreading operation is lessened, the racks -may be disengaged in a manner as heretofore set forth and then the hydraulic motor may be actuated to expedite the unthreading of the pipe sections, after which the gripping pistons may be released and the pipe removed by suitable manipulation of the valve 93 to release pressure against the pistons 15 and allow retraction of the compression of the helical springs 18, whereupon the pipe 98 may beremoved by suitable tools, as is well known in the art..

Summation of operation By way of summation of the operation, when the valve 93 is moved to cause actuation of the gripping pistons 15 on the pipe 98, the hydraulic motor 32 is actuated from a source of direct hydraulic pressure fluid (not shown), and as the torque increases in the make up connection, the motor 32 will start to stall. The valve is then moved to direct the flow of pressure fluid from the conduit 84 to the inlet port 63 of the motor cylinder 57, thereby moving the piston 62 and causing pivotal action of the cylinders 41 and 41 to cause movement of the rack members 45 and 45a into engagement with the gear wheel 8. Subsequentdischarge of the pressure fluid from port 63 through the ports 67, 74, conduit 101 and to ports 7'5 and 78 will move the pistons 48 and 48a in opposite directions, or in a left and right hand direction, respectively, in accordance with Fig. 1, thereby providing an increase in torque to continue rotation of the gear wheel .8 in a clockwise direction.

The rotation of the gear wheel. 8 will continue until the torque and the pressure are increased sufiiciently for the adjustable pressure relief valve 103 to relieve the pump 91 pumping the fluid from the tank 89. In this condition, retraction of the rack members can be made away from the gear wheel as has been previously set forth to remove the gripping apparatus from the pipe. However,

when. it is desired to unthread the joint, it is only necessary to again place the rack members 45 in engagement with the gear wheel 8 and change the porting of the valve 70 to cause movement of the pistons in a direction to provide counter-clockwise rotation of the gear wheel 8 during the initial unthreading operation which requires considerable or increased torque. The hydraulically actuated rack members will provide the required torque to cause the initial breaking or unthreading ofthe pipe joints, after which the rack members 45 and 45a can be retracted from the gear wheel, and the hydraulically actuated motor 32 can be adjusted for reverse rotation to continue the unthreading operation at an increased speed, thereby greatly expediting the operation.

The power stroke of the unit is to provide a threading or make up connection by movement of the pistons 48 and 48a and also to change the direction of the travel of the pistons for an unthreading connection. To accomplishthis, it is only necessary to reverse the interconnecting flow of the reversing valve 70 and there is no need to change the position of the four way valve 85. The valve 85 is only changed in position when it is necessary for retraction of the rack members by directing pressure fluid through inlet 65 in order to disengage the teeth 52 of the rack members from the teeth 13 of the gear wheel 8. The reversing valve 70 determines the direction of travel of the pistons when the racks are engaged and the power valve 57 determines the engagement of racks 45 and 45a with the gear Wheel 8. In the make up connection, hydraulic power fluid is always directed through inlet port 63 and out the port 67, whereas for disengagement of the rack teeth 52 in the retracting stroke, the hydraulic power fluid is discharged through the inlet port 65 and out the port 66.

It will be apparent that the power tong unit in operation might possibly cause rotation of the supporting structure in the oil well rig, such as the rotary table or the like. In order to prevent this, the unit is preferably utilized with any suitable type of back up means that will hold the table or supporting means stationary during an opera tion of the hydraulic power tongs. This back up means may be any suitable type of gripping means and forms no part of the present invention.

From the foregoing, it will be apparent that the present invention contemplates a hydraulically actuated power tong apparatus which is capable of applying variable degrees of torque and variable rotations to a power applicator gripping the pipe sections to be made up or unthreaded as is desired. Furthermore, the power gripping apparatus provides for a fast rotation in the initial make up connection of the pipe sections to be joined with a subsequent application of greater torque as needed. In similar manner, the gripping apparatus provides for an application of higher torque for breaking a joint between pipe sections in the initial unthreading operation with a subsequent higher rotation of the gripping apparatus for expediting the unthreading operation. Thus, it will be seen that the apparatus provides for an efiicient power gripping apparatus for making up or unthreading threaded joints with a considerable reduction in the necessary labor and time to perform these operations.

Changes may be made in the combination and arrangement of parts as heretofore set forth in the specification and shown in the drawings, it being understood that any modification in the precise embodiment of the invention may be made within the scope of the following'claims without departing from the spirit of the invention.

We claim:

1. In a power gripping apparatus for making and breaking threaded joints of pipe, the combination of: a base having a pipe receiving aperture, a gear wheel supported on the base and having an aperture in alignment with the base aperture, gripping pistons carried by the gear wheel, means for moving the gripping pistons radially respective to the pipe to alternately provide gripping engagement and a non-engagement therewith, means cooperating with the gear wheel to provide a fast rotation thereof during an initial make up connection between the joints of pipe, a second means cooperating with the gear wheel and responsive to increased torque requirements for the make up connection to continue rotation of the gear wheel for completing the make up connection, said second means comprising a pair of actuating pistons, a toothed rack member connected to each 'of the pistons and adapted to engage the gear wheel at diametrically opposite sides thereof for alternately driving the gear wheel in opposite directions, and means cooperating with the actuating pistons for moving the pistons and the rack members in a direction for rotating the gear wheel in a clockwise direction to make up the connection.

2. In a power gripping apparatus for making and breaking threaded joints of pipe, the combination of: a base having a pipe receiving aperture, a gear wheel supported on the base and having anaperture in alignment with the base aperture, gripping pistons carried by the gear wheel, means for moving the gripping pistons radially respective to the pipe to alternately provide a gripping engagement and a non-engagement therewith, means cooperating with the gear wheel to provide a fast rotation thereof during an initial make up connection between the joints of pipe, a second means cooperating with the gear wheel and responsive to increased torque requirements for the make up connection to continue rotation of the gear wheel for completing the make up connection, said second means comprising a pair of actuating pistons, a toothed rack member connected to each of the pistons and adapted to engage the gear wheel at diametrically opposite sides thereof for alternately driving the wheel in opposite directions, and means cooperating with the actuating pistons to provide movement of the pistons with simultaneous movement of the rack members for rotation of the gear wheel, said means responsive to variable adjustments for driving the pistons and rack members to rotate the gear Wheel alternately in clockwise and counter-clockwise directions.

3. In a power gripping apparatus for making and breaking threaded joints of pipe comprising in combination a base having a pipe receiving aperture, a rotatable gear wheel supported on the base and having an aperture in alignment with the base aperture, a plurality of circumferentially spaced gripping pistons carried by the gear wheel, hydraulic means for moving the gripping pistons radially respective to the pipe to alternately provide a gripping engagement and non-engagement therewith, a reversible hydraulically actuated motor cooperating with the gear wheel to provide a fast rotation thereof during an initial make up connection between the joints of pipe, means cooperating with the gear wheel and responsive to increased torque requirements for the connection to continue rotation of the gear wheel for completing the make up connection, said means comprising a pair of hydraulically actuated pistons, a rack member connected to each of the pistons and adapted toengage the outer periphery of the gear wheel at diametrically opposite sides thereof for alternately driving the gear wheel in opposite directions, cylinders for each of the actuating pistons, means connected with each of the piston cylinders to provide for pivotal movement of each of'the pistons in opposite directions to each other for alternately providing engagement and retraction of the rack members with the outer periphery of the gear Wheel, and means cooperating with the actuating pistons to provide movement of the pistons and rack members for rotation of the gear wheel, said means responsive to variable adjustments for driving the pistons and rack members to provide rotation of the gear wheel alternately in clockwise and counter-clockwise directions.

4. In a power gripping apparatus for making and gear wheel supported on the base and having an aperture in alignment with the base aperture, a plurality of circumferentially spaced gripping pistons carried by the gear wheel, hydraulic means for moving the gripping pistons radially respective to the pipe to alternately provide a gripping engagement and nonengagement therewith, a reversible hydraulically actuated motor cooperating with the gear wheel to provide a fast rotation thereof during an initial make up connection between the joints of pipe, means cooperating with the gear wheel and responsive to increased torque requirements for the connection to continue rotation of the gear wheel for completing the make up connection, said means comprising a pair of hydraulically actuated pistons, a rack member connected to each of the pistons and adapted to engage the outer periphery of the gear wheel at diametrically opposite sides thereof for alternately driving the gear wheel in opposite directions, cylinders for each of the actuating pistons, means connected with each of the piston cylinders to provide for pivotal movement of each of the pistons in opposite directions to each other for alternately providing engagement and retraction of the rack members with the outer periphery of the gear Wheel, and a four way valve suitably connected with a source of hydraulic pressure fluid and responsive to variable adjustments for driving the pistons and rack members to provide rotation of the gear wheel alternately in clockwise and counterclockwise directions.

5. In a power gripping apparatus for making and breaking threaded joints of pipe comprising in combination a base having a pipe receiving aperture, a rotatable gear wheel supported on the base and having an aperture in alignment with the base aperture, a plurality of circumferentially spaced gripping pistons carried by the gear wheel, hydraulic means for moving the gripping pistons radially respective to the pipe to alternately provide a gripping engagement and non-engagement therewith, a reversible hydraulically actuated motor cooperating with the gear wheel to provide a fast rotation thereof during an initial make up connection between the joints of pipe, means cooperating with the gear wheel and responsive to increased torque requirements for the connection to continue rotation of the gear wheel for completing the make up connection, said means comprising a pair of hydraulically actuated pistons, a rack member connected to each of the pistons and adapted to engage the outer periphery of the gear wheel at diametrically opposite sides thereof for alternately driving the gear wheel in opposite directions, cylinders for each of the actuating pistons, a hydraulically actuated power valve, a source of hydraulic pressure therefor, said power valve connected with each of the actuating piston cylinders and responsive to variable adjustments to provide for pivotal movement of each of the piston cylinders in opposite directions to each other for alternately providing engagement and rectraction of the rack members with the outer periphery of the gear wheel.

6. In a pipe gripping assembly for threading and unthreading sections of pipe comprising a rotatably gripping unit having a pipe receiving passage therethrough, means for gripping the pipe therein, means for providing a two stage rotation of the gripping unit in both the make up threading and the unthreading operations between the pipe joints, said means comprising a reversible fluid driven motor operably connected to the pipe gripping unit to rotate said pipe gripping unit in either direction in one stage of the operation, and a plurality of fluid driven pistons having operably connected members cooperating with the pipe gripping unit for alternately driving the pipe gripping unit in a clockwise and counterclockwise direction.

7. In a pipe gripping assembly for threading and unthreading sections of pipe comprising a rotatable gripping unit having a pipe receiving passage therethrough, means for gripping the pipe therein, means for providing a two stage rotation of the gripping unit in both the make up threading and unthreading operations between the pipe joints, said means comprising a reversible fluid driven motor operably connected to the pipe gripping unit to rotate the gripping unit at an increased speed of rotation alternately in the initial stage of the make up connection and finally in the unthreading operation, and a plurality of fluid driven postons having operably connected members cooperating with the pipe gripping unit for alternately driving the pipe gripping unit in a clockwise and counterclockwise direction.

8. In a pipe gripping assembly for threading and unthreading sections of pipe comprising a rotatable gripping unit having a pipe receiving passage therethrough, means for gripping the pipe therein, means for providing a two stage rotation of the gripping unit in both the make up threading and the unthreading operations between the pipe joints, said means comprising a reversible fluid driven motor operably connected to the pipe gripping unit to rotate said pipe gripping unit in either direction in one stage of operation, a plurality of pivotal cylinders having fluid driven pistons therein cooperating with rack members operably connected to the pipe gripping unit, means for pivotally moving said cylinders to alternately engage and disengage the rack members with the pipe gripping unit, and means to provide movement of the fluid driven pistons in variable directions to cause rotation of the pipe gripping unit alternately in a clockwise and counterclockwise direction.

9. In a pipe gripping assembly for threading and unthreading sections of pipe comprising a rotatable gripping unit having a pipe receiving passage therethrough, means for gripping the pipe therein, means for providing a two stage rotation of the gripping unit in both the make up threading and the unthreading operations between the pipe joints, said means comprising a reversible fluid driven motor operably connected to the pipe gripping unit to rotate said pipe gripping unit in either direction in one stage of operation, a plurality of pivotal cylinders having fluid driven pistons therein cooperating with rack members operably connected to the pipe gripping unit, means for pivotally moving said cylinders to alternately engage and disengage the rack members with the pipe gripping unit, means to provide movement of the fluid driven pistons in variable directions to cause rotation of the pipe gripping unit alternately in a clockwise and counterclockwise direction, and a source of pressure fluid supplying said last mentioned means.

References Cited in the file of this patent UNITED STATES PATENTS 2,639,894 Smith May 26, 1953 2,649,283 Lundeen Aug. 18, 1953 2,691,314 Stevens et al. Oct. 12, 1954 2,720,803 Rice et a1 Oct. 18, 1955 2,737,839 Paget (1) Mar. 13, 1956 2,760,392 Paget (2) Aug. 28, 1956 2,780,950 Province Feb. 12, 1957 2,850,929 Crookston et a1 Sept. 9, 1958 

